A virtual reality environment presents a viewer with a computer-generated world with which the viewer may interact. Such a virtual reality environment is typically presented to the viewer via a pair of head-mounted displays, one for each eye, that present a three-dimensional (3D) image to the viewer. The head-mounted display also typically includes sensors to sense the viewer's head movements so that the viewer may explore the virtual reality environment by turning the viewer's head in a similar fashion as in the real world. Thus, for example, the viewer may look left or right in the virtual world by turning the viewer's head left or right, respectively.
An augmented reality environment presents a viewer with a limited amount of computer-generated objects that overlay onto the viewer's real-world view. The augmented reality environment may be presented to the viewer also via a pair of head-mounted displays, one for each eye, that present a 3D image to the viewer. The head-mounted displays may be transparent to allow the viewer to optically view the real world while the computer-generated objects are overlaid via the displays, or the head-mounted displays may display live images of the real world captured by video camera mounted proximate the head-mounted displays combined with the computer-generated objects overlaid onto the live images of the real world.